Not all harnesses are created equal. And there is no one-size-fits-all. A good harness should solve your context engineering problems. Understanding and optimizing lower-level details like system prompts, caching, and effective tool calling is how the harness stands out. This is why harness engineering is an important skill for AI engineers today. Start by building your own tiny/minimal harness (in your favorite language) with a basic agent loop, system prompt, and tool calling…